Polyethyleneimine-modified pectin beads for colon-specific drug delivery:In vitroandin vivoimplications

Green synthesis of metallic nanoparticles using pectin as a reducing agent: a systematic review of the biological activities

CONTEXT

Pectin is a plant heteropolysaccharide that is biocompatible and biodegradable, enabling it to be an excellent reducing agent (green synthesis) for metallic nanoparticles (MNPs). Nevertheless, in the biological industry, pectin has been left behind in synthesising MNPs, for no known reason.

OBJECTIVE

To systematically review the biological activities of pectin synthesised MNPs (Pe-MNPs).

METHODS

The databases Springer Link, Scopus, ScienceDirect, Google Scholar, PubMed, Mendeley, and ResearchGate were systematically searched from the date of their inception until 10^th February 2020. Pectin, green synthesis, metallic nanoparticles, reducing agent and biological activities were among the key terms searched. The data extraction was focussed on the biological activities of Pe-MNPs and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations for systematic reviews.

RESULTS

A total of 15 studies outlined 7 biological activities of Pe-MNPs in the only three metals that have been explored, namely silver (Ag), gold (Au) and cerium oxide (CeO₂). The activities reported from the in vitro and in vivo studies were antimicrobial (9 studies), anticancer (2 studies), drug carrier (3 studies), non-toxic (4 studies), antioxidant (2 studies), wound healing (1 study) and anti-inflammation (1 study).

CONCLUSIONS

This systematic review demonstrates the current state of the art of Pe-MNPs biological activities, suggesting that Ag and Au have potent antibacterial and anticancer/chemotherapeutic drug carrier activity, respectively. Further in vitro, in vivo, and clinical research is crucial for a better understanding of the pharmacological potential of pectin synthesised MNPs.

Resveratrol for cancer therapy: Challenges and future perspectives

Resveratrol (3,4',5-trihydroxy-trans-stilbene) has been expected to ameliorate cancer and foster breakthroughs in cancer therapy. Despite thousands of preclinical studies on the anticancer activity of resveratrol, little progress has been made in translational research and clinical trials. Most studies have focused on its anticancer effects, cellular mechanisms, and signal transduction pathways in vitro and in vivo. In this review, we aimed to discern the causes that prevent resveratrol from being used in cancer treatment. Among the various limitations, poor pharmacokinetics and low potency seem to be the two main bottlenecks of resveratrol. In addition, resveratrol-induced nephrotoxicity in multiple myeloma patients hinders its further development as an anticancer drug. New insights and strategies have been proposed to accelerate the conversion of resveratrol from bench to bedside. In the interim, the most promising approach is to enhance the bioavailability of resveratrol with new formulations. Alternatively, more potent analogues of resveratrol could be developed to augment its anticancer potency. Given all the gaps mentioned, much work remains to be done. However, if remarkable progress can be made, resveratrol may finally be used for cancer therapy.

Pectin based multi-particulate carriers for colon-specific delivery of therapeutic agents

In case of colon-specific delivery of therapeutic agents through oral route, microbial/enzyme-triggered release approach has several advantages over other approaches due to unique microbial ecosystem in the colon. Multiple-unit carriers have an edge over single-unit carriers for this purpose. Among different materials/polymers explored, pectin appears as a promising biopolymer to construct microbial-triggered colon-specific carriers. Pectin is specifically degraded by colonic enzymes but insusceptible to upper gastro-intestinal enzymes. In this article, utilization of pectin solely or in combination with other polymers and/or colonic-delivery approaches is critically discussed in detail in the context of multi-particulate systems. Several studies showed that pectin-based carriers can prevent the release of payload in the stomach but start to release in the intestine. Hence, pectin alone may construct delayed release formulation but may not be sufficient for effective colon-targeting. On the other hand, combination of pectin with other materials/polymers (e.g., chitosan and Eudragit® S-100) has demonstrated huge promise for colon-specific release of payload. Hence, smartly designed pectin-based multi-particulate carriers, especially in combination with other polymers and/or colon-targeting approaches (e.g., microbial-triggered + pH-triggered or microbial-triggered + pH-triggered + time-release or microbial-triggered + pH-triggered + pressure-based), can be successful colon-specific delivery systems. However, more clinical trials are necessary to bring this idea from bench to bedside.

Microemulsion composed of combination of skin beneficial oils as vehicle: Development of resveratrol-loaded microemulsion based formulations for skin care applications

Microemulsion can be a potential delivery vehicle to deliver skin care actives to deep skin layer for chronic skin care benefits. On top of skin care active, microemulsion vehicle composed of multiple skin beneficial oils can deliver additional skin care efficacies. In this study, microemulsions were developed using combinations of two skin beneficial oils, tea tree oil and medium chain triglyceride instead of single oil. For that, pseudo ternary phase diagrams were constructed on these oil combinations at different ratios of surfactant/co-surfactants. Ratio of oils and surfactant/co-surfactant combinations exhibited significant impact on the microemulsion region. A few compositions were selected from the single phase microemulsion regions of these phase diagrams for the preparation of resveratrol-loaded microemulsion and microemulsion gel formulations. The particle size of the resveratrol-loaded microemulsions were <50 nm. Cryogenic scanning electron microscope image clearly showed nano-droplets dispersed in continuous phase. Both physical and chemical stability of the formulations varied depending on their compositions, such as surfactant/co-surfactant combination and % total oil. The presence of chelating agent and anti-oxidant was also crucial to stabilize the formulations. The selected formulations demonstrated good physicochemical stability at 5 °C, 25 °C, and 40 °C/75 % RH (relative humidity) stability conditions. The results further showed that the % total oil and surfactant phase composition had huge influence on resveratrol release and skin permeation patterns from the microemulsion gels. In vitro skin permeation result indicated that the microemulsion gels can help resveratrol penetration into deep skin layer. Therefore, the developed resveratrol-loaded microemulsion gels can be utilized as skin care product with multiple skin care benefits.

Colon-targeting of progesterone using hybrid polymeric microspheres improves its bioavailability and in vivo biological efficacy

This study aims to enhance progesterone (PG) oral bioavailability via its incorporation into hybrid colon-targeted pectin/NaCMC microspheres (MS) cross-linked with Zn²⁺ and Al³⁺. The MS were characterized for particle morphology, encapsulation efficiency, swelling behavior, drug release, mucoadhesivity and colon-specific degradability. Response-surface methodology was adopted to optimize the fabrication conditions. Enhancement of in vivo drug performance was evaluated through pharmacokinetic and pharmacodynamic studies. The optimized formulation was typically spherical with a mean diameter of 1031 µm and drug entrapment efficiency of 88.8%. This formulation exhibited pH-dependent swelling, negligible drug release in simulated gastric fluid and sustained-release pattern in simulated small intestinal fluid with a mean t_50% of 26.5 h. It also showed prolonged and preferential adhesion to rat colonic mucosa, as well as expedited degradation in presence of rat caecal contents. The MS significantly increased the area under the curve and mean residence time by 1.8 and 2.3-fold, respectively compared to the free drug. Orally administered MS showed ~10 times increase in myometrial thickness compared with the drug suspension and elicited uterine responses very similar to that obtained parenterally. These results confirm the ability of this new carrier system to improve the oral bioavailability of PG and attain adequate clinical efficacy.

Antioxidant activity and photostability assessment of trans-resveratrol acrylate microspheres

Trans-resveratrol (RSV) was microencapsulated in Eudragit^® RS100 and RL100 resin blends. Lyophilized microspheres were characterized in the solid state for their micromeritic properties and drug loading. FT-IR, PXRD, and DSC analyzes suggested that RSV formed an intimate microcrystalline dispersion within the polymer network, also confirmed by SEM analysis. This produced a reduced degradation of RSV after storage at 40 °C, compared to the neat drug, and a protection of the drug from UV light-induced trans-cis isomerization (60% intact drug was found after 60 s irradiation at 350 nm, compared to 37% for the pure drug). Solubility and in vitro dissolution studies indicated that microencapsulation did not improve the dissolution pattern of RSV in simulated gastric and intestinal aqueous fluids. Evaluation of the in vitro antioxidant activity showed that, compared to the neat drug in aqueous solution, RSV loaded in the microspheres retained for a longer time, up to 22 days of incubation, the initial ORAC capacity. The present study thus demonstrated that Eudragit^® Retard resins can be used to easily produce micro-sized solid dispersions with RSV, for potential oral administration, contributing to ameliorate the physico-chemical stability and antioxidant activity of this compound.

Green synthesis of folic acid-conjugated gold nanoparticles with pectin as reducing/stabilizing agent for cancer theranostics

The one pot aqueous green synthesis of gold nanoparticles (GNPs) decorated with folic acid and loaded with doxorubicin suitable for anti-cancer drug delivery was potentially promising as a new therapeutic system for cancer treatment.

Acetal derivatives as prodrugs of resveratrol

The pharmacological exploitation of resveratrol is hindered by rapid phase-II conjugative metabolism in enterocytes and hepatocytes. One approach to the solution of this problem relies on prodrugs. We report the synthesis and characterization as well as the assessment of in vivo absorption and metabolism of a set of prodrugs of resveratrol in which the OH groups are engaged in the formal (-OCH2OR) or the more labile acetal (-OCH(CH3)OR) linkages. As carrier group (R) of the prodrug, we have used short ethyleneglycol oligomers (OEG) capped by a terminal methoxy group: -O-(CH2CH2O)n-CH3 (n = 0, 1, 2, 3, 4, 6). These moieties are expected to exhibit, to a degree, the favorable properties of longer polyethyleneglycol (PEG) chains, while their relatively small size makes for a more favorable drug loading capacity. After administration of formal-based prodrugs to rats by oral gavage, significant concentrations of derivatives were measured in blood samples over several hours, in all cases except for n = 0. Absorption was maximal for n = 4. Complete deprotection to give resveratrol and its metabolites was however too slow to be of practical use. Administration of the acetal prodrug carrying tetrameric OEG chains resulted instead in the protracted presence of resveratrol metabolites in blood, consistent with a progressive regeneration of the parent molecule from the prodrug after its absorption. The results suggest that prodrugs of polyphenols based on the acetal bond and short ethyleneglycol oligomers of homogeneous size may be a convenient tool for the systemic delivery of the unconjugated parent compound.

Cationic polymers and their therapeutic potential

The last decade has witnessed enormous research focused on cationic polymers. Cationic polymers are the subject of intense research as non-viral gene delivery systems, due to their flexible properties, facile synthesis, robustness and proven gene delivery efficiency. Here, we review the most recent scientific advances in cationic polymers and their derivatives not only for gene delivery purposes but also for various alternative therapeutic applications. An overview of the synthesis and preparation of cationic polymers is provided along with their inherent bioactive and intrinsic therapeutic potential. In addition, cationic polymer based biomedical materials are covered. Major progress in the fields of drug and gene delivery as well as tissue engineering applications is summarized in the present review.

Administration of resveratrol: What formulation solutions to bioavailability limitations?

Resveratrol (3,5,4'-trihydroxystilbene), a naturally occurring polyphenol, has attracted considerable interest for its beneficial potentials for human health, which include anti-oxidant, anti-inflammatory, cardioprotective and anti-tumor activities. However, the in vivo biological effects of resveratrol appear strongly limited by its low bioavailability, which is a barrier to the development of therapeutic applications. In this context, an increasing number of recent studies have aimed at designing novel resveratrol formulations to overcome its poor solubility, limited stability, high metabolization and weak bioavailability. This review outlines physicochemical and pharmacokinetic limitations to resveratrol bioavailability, describes formulations tested for resveratrol administration, controlled release and targeting, and identifies future opportunities for resveratrol delivery.